http://l2.espacenet.com/espacenet/viewer?PN=CN1132740&CY=gb&LG=en&DB=EPD (http://l2.espacenet.com/espacenet/viewer?PN=CN1132740&CY=gb&LG=en&DB=EPD)
http://l2.espacenet.com/espacenet/viewer?PN=IN185200&CY=gb&LG=en&DB=EPD (http://l2.espacenet.com/espacenet/viewer?PN=IN185200&CY=gb&LG=en&DB=EPD)
http://l2.espacenet.com/espacenet/viewer?PN=CN1364756&CY=gb&LG=en&DB=EPD (http://l2.espacenet.com/espacenet/viewer?PN=CN1364756&CY=gb&LG=en&DB=EPD)
http://www.mayallj.freeserve.co.uk/china.htm (http://www.mayallj.freeserve.co.uk/china.htm)